The invention relates to classifiers, particularly though not exclusively classifiers applicable to the classification of particulate cement.
Many conventional classifiers have a rotor mounted in a housing which has a relatively large hopper beneath the rotor for collecting the coarser particles of material being classified. Consequently, the overall height of such a classifier is relatively large and the associated support structure and the additional duct work required lead to high capital expenditure.
Classifiers which do not use a hopper are known (for example, see UK Pat. No. 515717). In developing such a classifier, the Applicants found that the efficiency of classification was relatively low owing to relatively large amounts of product-size (i.e. finer) particles leaving the classifier through the outlet opening for coarser particles.